ABSTRACT The Pathways Study is a prospective cohort study of women diagnosed with first primary invasive breast cancers in the Kaiser Permanente Northern California (KPNC) medical care system. Enrolled from January, 2006 through May, 2013, the 4,505 women in the cohort are diverse racially and ethnically, and include 358 (8.0%) African American, 557 (12.4%) Latina, and 578 (12.8%) Asian women. Data have been collected on food intake, physical activity, use of nutritional supplements and complementary and alternative modalities (CAM), and patient-reported factors such as quality of life, social support, and doctor-patient communications. Biospecimens collected from almost all cohort members and banked in the study biorepository at Roswell Park Cancer Institute (RPCI) include blood (n=4,034, or 90% of the cohort), saliva (n=4,310, or 96%), and extracted germline DNA (n=4,437, or 99%). Baseline addresses have been geocoded and linked to contextual databases to create neighborhood-level social and built environment variables. The KPNC setting provides access to electronic medical records (EMRs), with data available on diagnostic characteristics, treatment such as specific chemotherapy agents and doses, hormone therapy, high-grade toxicities, and comorbid conditions. As of December 31, 2014, 369 recurrences, 213 second primary invasive cancers, and 469 deaths have been identified in this cohort, with 751 women with at least one of these outcomes. In this infrastructure grant, we propose to maintain and augment the Pathways Study to support a growing research program that builds upon this resource. Study participants will continue to be followed for occurrence of outcomes through KP medical records and annual follow-up questionnaires. Follow-up for updated quality-of-life and other patient-reported measures such as changes in lifestyle factors will continue through 96 months post-enrollment for those who have not yet passed that milestone. We will augment biospecimen resources with a follow-up blood sample for examination of long-term molecular factors, establishing a tumor specimen bank from all cohort members, and by immunohistochemistry assays to subtype tumors. We will enhance data resources with ongoing linkage with databases from KP electronic medical records; by incorporating genotypic data to be obtained from the Center for Inherited Disease Research (separate grant received an Impact Score of 23); and by updating contextual data for the cohort. We will establish an external advisory board and a community and participant advisory board to help guide infrastructure activities and prioritize research use of this cohort. We will also establish a consortium of breast cancer prognosis epidemiology cohort studies to enhance the ability to examine associations in subgroups of breast cancers. Ongoing support will enhance the unique and outstanding resource that is the Pathways Study, and facilitate its availability for the broader research community.